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Extreme polymorphism in a Y-linked sexually selected trait
A K Lindholm1, R Brooks, F Breden
1Behavioural Ecology Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada. anna.lindholm@unsw.edu.au
Heredity
|January 22, 2004
Summary
Male Poecilia parae fish display complex color variations, with Y-chromosome linked traits influencing reproductive success. Female preferences for rare morphs are overridden by other mating strategies, impacting population dynamics.
Area of Science:
- Evolutionary Biology
- Genetics
- Animal Behavior
Background:
- Livebearing fish, Poecilia parae, exhibit striking male color polymorphisms.
- Females of this species are monomorphic, presenting a contrast to male diversity.
Purpose of the Study:
- To describe male color morphs and size dimorphism in Poecilia parae.
- To determine the genetic basis and inheritance pattern of male color polymorphism.
- To investigate the fitness consequences and female mating preferences associated with different male morphs.
Main Methods:
- Pedigree analysis to establish Y-chromosome linkage of color polymorphism.
- Field surveys across multiple populations in South America to assess morph abundance.
- Offspring rearing and dichotomous choice tests to evaluate reproductive success and female preference.
Main Results:
- Five distinct male color morphs and associated size dimorphism were identified.
- The male color polymorphism is genetically linked to the Y-chromosome.
- While females prefer rare morphs, the common morph exhibits higher reproductive success, suggesting overridden preferences.
Conclusions:
- The Y-linkage of color polymorphism in Poecilia parae supports theories of sexually antagonistic traits on heterogametic sex chromosomes.
- Complex interactions including alternative mating strategies and sperm competition likely influence observed morph frequencies and reproductive outcomes.